Zebrafish (Danio rerio) as an animal model for bath infection by Flavobacterium psychrophilum

Ruben Avendaño-Herrera, Isabel Benavides, Jaime A. Espina, Daniela Soto-Comte, Matías Poblete-Morales, Juan A. Valdés, Carmen G. Feijóo, Ariel E. Reyes

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


Flavobacterium psychrophilum is the causative agent of bacterial cold-water disease and rainbow trout syndrome in freshwater salmonid fish worldwide, generating injuries and high mortality rates. Despite several studies on this bacterium, the infection mechanism remains unknown due to limitations in the employed animal models. In this work, we propose using zebrafish (Danio rerio) as a model for studying bacterial pathogenicity. To substantiate this proposal, zebrafish infection by F. psychrophilum strain JIP 02/86 was characterized. Zebrafish larvae were infected using the bath method, and morphological changes and innate immune system activation were monitored using transgenic fish. Salmonid-like infection phenotypes were observed in 4.74% of treated larvae, as manifested by fin, muscle and caudal peduncle damage. Symptomatic and dead larvae accounted for 1.35% of all challenged larvae. Interestingly, infected larvae with no infection phenotypes showed stronger innate immune system activation than specimens with phenotypes. A failure of function assay for myeloid factor pu.1 resulted in more infected larvae (up to 43.5%), suggesting that low infection rates by F. psychrophilum would be due to the protective actions of the innate immune system against this bacterium in zebrafish larvae. Our results support the use of zebrafish as an infection model for studying F. psychrophilum. Furthermore, the percentage of infected fish can be modulated by disturbing, to varying extents, the differentiation of myeloid cells. Using this evidence as a starting point, different aspects of the infection mechanism of F. psychrophilum could be studied in vivo.

Original languageEnglish
Article numberDOI: 10.1111/jfd.13156
Pages (from-to)561-570
Number of pages10
JournalJournal of Fish Diseases
Issue number5
Publication statusPublished - May 2020


  • aquaculture
  • bacterial cold-water disease
  • immersion bath
  • rainbow trout fry syndrome

ASJC Scopus subject areas

  • Aquatic Science
  • veterinary (miscalleneous)


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